As is standard in a retriever–reader design, the retriever in [1]} returns \(k\)  candidate passages (i.e., splits from Wikipedia) for each query \(q\) .
The reader extracts the final answer span from these candidate contexts, where each context \(C_i\)  is comprised of the Wikipedia article title \(C_i^\textrm {title}\)  and the content text \(C_i^\textrm {text}\) .
